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presence peak in sdc mics Condenser Microphones
Old 1 week ago
  #1
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Thread Starter
presence peak in sdc mics

Why a lot of sdc mics have a presence peak in higher frequencies?
For example the Neumann KM184. Is for this feature that it's often described as harsh?
This this peak useful when these mics are placed away from the source, for example in a stereo main couple? And it's excessive when used near an instrument?
Old 1 week ago
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Yannick's Avatar
 

I’ve thought about this for 25 years, and still did not come up with an answer.
Old 1 week ago
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Part of it is historic, from the days when we tracked to magnetic tape - mics which had a high end lift became preferred as they came across as cleaner on tape and helped cut through mixes which could become dull sounding due to multiple sub mixing and bounces. As digital became the norm, there was still a lot of holdover which preferred brighter mics for vocal recording and for certain instruments such as acoustic guitar. In the classical world, a high end lift can help overcome high freq loss due to distance, eg diffuse field mics vs nearfield mics. So, generally, somewhat brighter mics will often be a better choice for mid-distance ensemble micing, whereas flatter mics will usually be more effective spot mics. So, while the km184 might not be a good choice for spotting a piccolo (ouch), an ORTF pair of 184s can be quite good for small ensemble or orchestral work.
Old 1 week ago
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Because it's cheaper & easier to design a SDC that way.

The best SDC (KM84) handles this by rolling of the highs as the signal gets louder. the AA1084 copied this design and circuit for the same effect. This solves the peak problem. That mic's has not been heard by most yet, including myself. The only reason I know this is from a talk with Dave Thomas when he was finishing up the design of that mic.

The newer 184 does not have circuit.

The quality control required to make a small cap good is not easy. In theory, a SDC is the best mic design because of low mass. But only with good QA that costs lots of cash. Good SDC's are typically more than $1,000.


I recently purchased a very unusual SDC I'm waiting to test out when my system is complete. A Russian SDC mic (206 I think) that is designed for kick and can take 173 SPL.
Old 1 week ago
  #5
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Because of the diameter and thickness of the diaphragm membrane in relationship to the magnetic strength of the back-plate, as well as the acoustic properties of the metal tube that is the mic body. The more expensive (complex/engineered) the body/mount, electronics and capsule, the more this is compensated for. Same reason LDCs tend to have a mid scooped effect. Well LDCs have a few other physical and electronic design properties in addition to those contributing factors to frequency specific sensitivity found in SDCs.
Old 1 week ago
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If someone could come up with a mod that tamed the HF rise of the NT5 cardioid, I'd be listening !

I suspect it might involve drilling (or plugging) holes in the backplate...or changing the size of the 'breathing gills around the neck' with a hacksaw blade Jim Williams...any ideas ?
Old 1 week ago
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Quote:
Originally Posted by elegentdrum View Post
A Russian SDC mic (206 I think) that... can take 173 SPL.
I guess it's good to know if someone tosses a Stun Grenade into the studio in the middle of a take, there's a mic that can keep recording without distorting!
Old 1 week ago
  #8
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AKG C451 was a very popular modular mic with brilliant in vision solutions
Hence it was a TV favourite in the 80/90s
It had considerable brightness, this added to a presence lift on AMPEX VTRs and the helical formation of the tape gave characteristic quality to VT sound
Nobody to my knowledge eq'd it
When film sound (Sennheiser MKH RF) met VT sound in a programme it was bleeding obvious
Roger
Old 1 week ago
  #9
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Thread Starter
Quote:
generally, somewhat brighter mics will often be a better choice for mid-distance ensemble micing, whereas flatter mics will usually be more effective spot mics. So, while the KM184 might not be a good choice for spotting a piccolo (ouch), an ORTF pair of 184s can be quite good for small ensemble or orchestral work.
So who says that the KM184 is harsh probably is using it for near micing (a guitar for example), but it's good if used as stereo pair because the peak over 8khz compensates the loss of higher frequencies due to the distance.
I suppose that if used as main stereo the KM184 isn't too harsh (?)
Old 1 week ago
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Compared to the rest of the MKH series, I find the MKH800 bright, because of a slight HF lift, and bump at 20 K.

I nearly always EQ this out, close mic or far field. Somehow it strikes me as odd to make a more distant recording, and then (overcompensate) the slight HF loss.

Most often a recording already sounds brighter than an audience perspective, as the main mics are generally quite close and way up high.

The only explanation I find for all these mics with hf lifts is, either it is a remnant of old tape/vinyl days, where most loudspeakers also did not have great hf extension; or to compensate a certain lack in transparancy (in the recording chain or the playback chain ?).

Anyway, I generally do not like it, even not in my favorite mics.
Old 1 week ago
  #11
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Quote:
Originally Posted by Yannick View Post
I nearly always EQ this out, close mic or far field. Somehow it strikes me as odd to make a more distant recording, and then (overcompensate) the slight HF loss.

Most often a recording already sounds brighter than an audience perspective, as the main mics are generally quite close and way up high.

The only explanation I find for all these mics with hf lifts is, either it is a remnant of old tape/vinyl days, where most loudspeakers also did not have great hf extension; or to compensate a certain lack in transparancy (in the recording chain or the playback chain ?).

Anyway, I generally do not like it, even not in my favorite mics.
Here is a good supporting article for this outlook, with measurements and graphical data:

Records and Reality
Old 1 week ago
  #12
Quote:
Originally Posted by studer58 View Post
If someone could come up with a mod that tamed the HF rise of the NT5 cardioid, I'd be listening !

I suspect it might involve drilling (or plugging) holes in the backplate...or changing the size of the 'breathing gills around the neck' with a hacksaw blade Jim Williams...any ideas ?
Outside of more simple EQ cap roll-offs, a new capsule is about all one could do. Some are just made that way. Even the older B+K 4006/4003 has a bell bump at 16k hz. Most don't mind as it's not that noticeable. Drop it to 10k hz and it's a problem. Then there is the effect of the electronics too. Older fet amps are more dirty than some newer stuff. Parts choices also affect the sonics like tantalum vs film caps.

Schoeps 1/2" is pretty flat as are the CK-6x AKG capsules. Too bad someone doesn't make adaptor rings to interface to each other.
Old 1 week ago
  #13
Quote:
Originally Posted by studer58 View Post
If someone could come up with a mod that tamed the HF rise of the NT5 cardioid, I'd be listening !

I suspect it might involve drilling (or plugging) holes in the backplate...or changing the size of the 'breathing gills around the neck' with a hacksaw blade Jim Williams...any ideas ?
The Joly replacement capsules are a decent improvement. I quit using the cardioid caps with my pair, until I got those. I like the omni caps pretty well, though.
Old 1 week ago
  #14
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Quote:
Originally Posted by edwinhurwitz View Post
The Joly replacement capsules are a decent improvement. I quit using the cardioid caps with my pair, until I got those. I like the omni caps pretty well, though.
Yes I'd considered those a while ago, although the price wasn't that far off a whole new pair of NT5's.

The sound samples on his site Award-winning microphone engineering from Michael Joly were pleasant, but I wondered if a shelving cut around 8k on the standard capsules wouldn't achieve the same result ?

Then I heard these 2 samples (post #57 , link below), and found the differences somewhat disturbing !
Michael Joly Engineering MJE-384

Quite a lift in the bass, at least when used up close....
Old 1 week ago
  #15
Quote:
Originally Posted by studer58 View Post
Yes I'd considered those a while ago, although the price wasn't that far off a whole new pair of NT5's.

The sound samples on his site Award-winning microphone engineering from Michael Joly were pleasant, but I wondered if a shelving cut around 8k on the standard capsules wouldn't achieve the same result ?

Then I heard these 2 samples (post #57 , link below), and found the differences somewhat disturbing !
Michael Joly Engineering MJE-384

Quite a lift in the bass, at least when used up close....
Did you read where the poster thought his original capsules were bad because they were exceedingly thin? The flip side of that is a lift in bass. I wouldn't base my opinions on that comparison.
Old 1 week ago
  #16
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Quote:
Originally Posted by edwinhurwitz View Post
Did you read where the poster thought his original capsules were bad because they were exceedingly thin? The flip side of that is a lift in bass. I wouldn't base my opinions on that comparison.
No, but I would base them on what Joly himself says: https://messageboard.tapeop.com/viewtopic.php?t=85106

"These capsule replace the stock RODE NT5 capsules - just screw them on, no need to send in your NT5 mics. People asked me for years to come up with a modification for the RODE NT5 that would tame the high end and add some missing bass. I always declined because I didn't have an elegant solution.

But this past Fall I put the thinking cap on and came up with the MJE-384K capsules for the NT5. They feature my "directview" diaphragm placement which eliminates diaphragm set-back coloration and also feature my new-design backplate which provides extended bass response, very flat mid-to-top end response, gets rid of the HF peak in the NT5 and supplies some missing very top end "air".

You can hear them in action vs. the Schoeps CMC-6 with MK-4 capsule at my site.

Enjoy! best, Michael"

...so it would seem, at least to some extent, a bass lift is engineered in.
Old 1 week ago
  #17
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Quote:
Originally Posted by elegentdrum View Post
Because it's cheaper & easier to design a SDC that way.

The best SDC (KM84) handles this by rolling of the highs as the signal gets louder.
You've said that before on this forum, and as far as I know, it still isn't true.
Old 1 week ago
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Quote:
Originally Posted by psykostx View Post
Because of the diameter and thickness of the diaphragm membrane in relationship to the magnetic strength of the back-plate, as well as the acoustic properties of the metal tube that is the mic body. The more expensive (complex/engineered) the body/mount, electronics and capsule, the more this is compensated for. Same reason LDCs tend to have a mid scooped effect. Well LDCs have a few other physical and electronic design properties in addition to those contributing factors to frequency specific sensitivity found in SDCs.
er... what?

A capacitor mic is just that -- a (variable) capacitor. The backplate is not magnetic and even if it was the diaphragm wouldn't be affected by magnetism, since it is sputtered with non-ferrous metal (usually gold).
Old 6 days ago
  #19
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Originally Posted by Peller View Post
er... what?

A capacitor mic is just that -- a (variable) capacitor. The backplate is not magnetic and even if it was the diaphragm wouldn't be affected by magnetism, since it is sputtered with non-ferrous metal (usually gold).
You're correct, the magnetic component of the field is irrelevant, I meant the field strength, which does indeed have an effect on impulse response and recovery from transients, as well as the amount of DC offset that needs to be compensated for. However, every capacitor operates in flux, and every field has a magnetic component, so I wasn't technically incorrect there, only incorrect as to the relevance.
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